This invention relates to a tree delimbing apparatus of a type which can be mounted on a vehicle and moved over a plurality of trees in a longitudinal direction of the trees and includes a plurality of blades for stripping the limbs from the trees as the apparatus is moved along the trees.
Conventionally delimbing of the trees where necessary is carried out in many cases by inserting the tree into a separate fixed apparatus through which the tree is fed which includes suitable blades for stripping the limbs and leaving the bare trunk.
One proposal for a delimbing device for mounting on a vehicle is shown in Dakus U.S Pat. No. 4,172,478 which corresponds to Canadian Patent 1,105,363. This apparatus includes a frame which is attached to a vehicle of the type generally known as a skidder. The frame has a plurality of shafts mounted in parallel spaced relation with the shafts extending parallel to the direction of movement of the vehicle. Each shaft carries a single blade member which projects downwardly from the frame. The blade member is pivotally mounted on the shaft so that it can pivot around the axis of the shaft through a limited degree of movement moving to left or to right to accommodate the trees which sit generally between the blades. The blade is biased to an initial vertically depending position by a heavy spring arrangement mounted on the shaft so that the blade moves to left or to right only against the action of the spring.
This device solves some of the problems of the delimbing requirements but unfortunately is unsatisfactory for a number of reasons. Firstly the presence of the springs significantly increases the cost and complication of the device and furthermore the springs are prone to breakage and damage leading to increased maintenance costs. Secondly the delimbing action takes place generally only over the sides of the trees since the blades tend to remain in a substantially vertical orientation leaning only slightly to left or to right so that little or no possibility of the limbs on the underside of the tree being removed.